Stuck Throttles Discussion - Track Tech Q&A

I had just arrived at New Smyrna Speedway on the Thursday test day before the annual Governor's Cup races late last year. I was standing in turn one right next to the fence, not twenty feet from the track when Frank Kreyer went flying by, left front tire flattened, with his throttle stuck. He proceeded to hit the wall as hard as I've ever seen a race car hit.

2/4

The car continued around the outside wall shedding parts along the way and came to rest at the end of turn two. Frank got out, injured, and walked down the track and along the way, he threw down his HANS head-and-neck restraint in frustration at having destroyed a perfectly good race car.

3/4This is Frank Kreyer’s car just prior to his crash from a stuck throttle.

The only good thing I can say about that is that he was wearing a H&N restraint. That most definitely, in his opinion, saved his life. Two other drivers died in Florida in 2013 from hitting the wall at asphalt racetracks. They did not have on the required equipment and their families lost a loved one.

This is not a discussion about wearing a H&N device. It is to announce the beginning of a study as to why throttles stick. I will personally be talking to experts and racers about situation they have seen and/or experienced where the throttle stuck on a race car.

There are two primary areas to look at, one being interference with the throttle arm or linkage that moves that arm, and the other concerns the mechanisms on the carburetor locking the butterflies open where the driver can't return them to closed.

4/4The car just afterwards, a total loss.

I've heard several stories already about how the both of those situations have happened, but I'll wait to get all of the information from the appropriate experts as well as firsthand accounts, before I make my report. I don't think I have ever seen anyone address this situation, not that it hasn't, but I'm getting involved now.

Most everyone will agree that having a stuck throttle going full speed on any racetrack is right up there with the worst things that can happen. In almost every case, the car is destroyed in the process and if the driver is lucky, he is only injured. Countless drivers have lost their lives over the years from having their throttle stick open.

If there is anything that you need to pay very close attention to, it is the operation of your throttle linkage and carburetor. When the carb is off the car, you can operate the throttle arm from closed to full open several times to see if anything prevents it from closing. Nothing should impede a quick and friction free movement to closed.

Once the carb is installed, you should look over the entire linkage from pedal to throttle arm to see if there is anything that could interfere with the operation going from idle to full open throttle and back.

When the air cleaner is placed on the carb, again we need to inspect the area above the throttle arm to make sure there is proper clearance. The top cover of the air cleaner should have a stop under it on the threaded bolt coming up from the carb so that the bottom of the air cleaner can't be pushed down onto the throttle arm. The recess on the bottom of the air cleaner should be centered on the throttle arm too.

A few years ago, various companies offered a brake pressure operated kill switch that would kill the ignition if a certain level of brake pressure was induced. This was intended to help stop the acceleration when the throttle stuck. In Frank's case, he braked so hard that the left front tire deflated. I noticed that when I saw him go by. At first I thought that was why he could not turn in, but that was not the case.

Maybe it's time to rethink installing those devices. It may not keep the car from impacting the wall, because the event happens so quickly, but it would reduce the velocity of the car and minimize both the damage and the chance of injury to the driver. It is a simple device that is relatively cheap. In the 2013 Coleman catalog, it lists for $123.53. Let's see, a little over $100 or a $40,000 race car and motor? That's a tough decision.

The fact that you can never predict when your throttle will stick or how, the fastest and most efficient way to immediately deal with the situation and mitigate the damage is to be able to quickly kill the motor to stop the acceleration into the wall. The kill switch is the answer. You make the decision.

If you have comments or questions about this or anything racing related, send them to my email address: Bob.Bolles@sorc.com, or mail can be sent to Circle Track, Senior Tech Editor, 9036 Brittany Way, Tampa, FL 33619.

How to Find a Good Car to Purchase

I love reading your articles! I have been a crew chief for my friend's Dirt Mod for years now and have finally scrounged up enough to put a Sport Mod together. I know there are tons of chassis out there but how do you go about choosing from all these different types?

Obviously, I need to watch for bent ones and so on, but what are some good things to look for when choosing a frame in general?

Best wishes,—Eager rookie

Eager,

You might look for a chassis built by a reputable builder. Does it win races where you race? Then look at how the chassis has been maintained. Talk to the previous owner and see if it has been crashed hard, had clips replaced, etc. Those things tell you something about how hard a life the chassis has had.

You will need to see what the front and rear suspensions are built like. Are they adjustable for moment center location, rear steer, etc. Are there any cracks or bends in the chassis or control arms? And, how old is the chassis. The older it is, and the more it has been raced, the greater the chance that it will have damage or is just plain worn out.

The best cars to find are those where the previous owner bought the car new, raced it a limited number of times, never wrecked it, and now wants to get out of racing. You can usually pick up the car and many spare, also new, parts for cheap.

Also remember that a long time active racer will not sell you his/her best equipment or the winning setup that helped the car get those championships. Mainly just take your time and look at a lot of cars before deciding. That one special deal will come along.

Impala Street Stock Setup

I have been rebuilding an Impala framed Street Stock I bought last year. It is the complete stock Impala suspension with the exception of tubular upper A-arms with tall ball joints. I run 1,000-pound springs on both fronts and 250-pound LR and 200-pound RR. Scaling is around 53 percent all around. I raced it six nights with mediocre results.

The front stub was bent badly so I re-stubbed it myself along with changing the entire front and rear clips as well as x bracing the frame all to better the car and make it more safe. I have a few questions as I'm trying to get a good handle on the geometry of my car to be a consistent racer.

At the rear, I understand if I raise the front of the upper links it will lower the roll center. I believe I can achieve that by placing spring spacers on the top of the rear springs and try to get the upper trailing arms close to level which would be ideal. Correct me if I'm wrong.

Also what front suspension software would you suggest is the best bang for the buck? I plan on purchasing some to help me on this project.

I see where you preach that the rearend should be square and the handling will come by correcting the front end and spring choices both front and rear. The rearend on this car was jigged with the left side forward 1/2-inch when I bought it. It does help in the middle of the corners but does feel a little loose on the exits like you say it would be.

I just wanted your opinion on this matter as it seems to help me get through the corners faster. Our tracks are fairly dry slick by the time our class runs the feature so things have to be right on and I have to exercise good throttle control.

One last thing, I was told if you spread the tie rod portion on the spindles at least 1/2-inch out on each side this corrects Ackerman. Your opinion on this would be greatly appreciated. I was a subscriber to Circle Track for many years and have cut out many articles and enjoy reading them as well as online archives. Any advice you can give would be great.

Thank you,—Dennis Zelmer

Dennis,

The fact that it has aftermarket upper control arms up front as well as taller ball joints says something good about the front end. Look online and read the literature for each software that is available. You don't need one that is too complicated or you will get frustrated and not use it.

Once you get the front geometry fixed up, and the car is turning well, you won't need that crutch of moving the left rear wheel forward anymore. Make it a point to square that rearend so you'll have better bite off the corners.

Yes, the top view angle of the steering arms causes some of the Reverse Ackermann, but that might be counteracting Ackermann that is in the rest of the system. Moving those out will reduce that affect, but you might not need to. You can easily check your Ackermann with a string. You can find instructions on how to do this on www.circletrack.com.

As for the rear moment center, yes, raising the rear of the car will level out the trailing links and lower the rear MC, but it will also raise the center of gravity, which on dirt is not necessarily a bad thing. The spring rates you are running sound like they are in the ballpark for that design of car.

Try going to a 25-pound split in the rear (225 at the LR) and see if the car stays tight through the middle and off the corners, With the lower rear MC and a higher CG, you might not need that high of a rear spring split anymore.

Reducing the Cost of Racing

I feel that one of the major factors contributing to attendance and participation, or lack of, has to do with track management and costs. I have a few points and will try to make them brief.

1) You have mentioned "Rules." Sometimes they do need revising to stay current and sometimes cost efficient. Recently I moved to Kentucky and I was looking for a new track so I could bring my cars here. One major problem was the minimum wheelbase rule for the stock classes. The two tracks both had minimum wheelbase rules of 110 and 108 inches. My mid '80s T-bird and newer '86 Cougar were at 104 inches and were out!

The few that ran there were running '70s cars or the '80s and up Caprices/Crown Vics and I was told to just stretch the chassis. It's a unibody car! Finding these big old cars with the past/current scrap prices is getting nearly impossible, so allowing the somewhat shorter wheelbase later model cars to race only helps with costs.

I know Bob, you are a fan of allowing suspension modifications, but here is the cost thing again. If you're not a fabricator/welder then you are forced to pay a shop to do the work to keep up with those that can do it themselves. This is another major reason cars get parked.

2) Gate costs—As you're well aware, costs are a major issue these days. We lobbied for reduced gate fees but always ran into resistance. We constantly heard management say that it costs a lot of money to turn those lights on. Well it costs the same amount of money if there are 100 people in the stands at $18, or 1,000 people at $5.

In Pennsylvania, I've heard tracks having fan appreciation nights with admission being $1 or $2 and the attendance was described as sold out standing room only. Don't track officials want the stands and the dirt surrounding them packed with people every week?

Our track in south Jersey at the time charged us $18 front gate and $35-40 back gate. Some drivers were lucky to have one crew member but many had none.

When we raced in Pennsylvania, the front gate was $8 and the pits were $12 and the cars averaged 5-6 crew and their families and friends came too. Our track has got 20-plus cars and the Pennsylvania track got 70-plus. Our winner got $200 and the Pennsylvania winner got $1,000-plus and our track pays everyone a little bit. The Pennsylvania track only paid the top 10. Why does it seem some circle tracks feel the need to keep people out?

—Jim Erdbrink Jr.; Erdbrink Racing; Lebanon Junction, Ky.

Jim,

When a track has continually raised the price of admission for both the front and back gates, it is a gamble to go back to lower prices. In todays market, it is time to rethink those prices in lieu of our soft economy. But, they can have a special night and advertise low prices to test the market.

So, if like you say, instead of getting a couple hundred fans to show up, they lower the price to $5 and a thousand show up, then it might tell the owner something about how much the community wants to come, but can't afford the current prices.

Then, the management could lower the prices and offer other incentives to help keep those thousand fans coming back again and again. The increase in numbers not only brings in more admission money, those same fans will buy more hot dogs and cokes too. So now the owners double or triples their weekly income and once that happens, they can reduce the back gate fees to attract more race teams.

I'll never agree to stricter rules that prohibit the racer from being creative and working on their cars. I get your point about some not being able to weld, but that has always been a part of racing and race car fabrication. It might be time to learn that skill. I don't agree with having 20 crappy race cars just because a few can't learn to weld or find someone to work on the team who does know how.

The fact that you can never predict when or how your throttle will stick, the fastest and most efficient way to immediately deal with the situation and mitigate the damage is to be able to quickly kill the motor...